In 2012, while riding for the Bontrager Development team, Boswell finished 109th, second-to-last ahead of Radioshack's Gregory Rast and more than 25 minutes behind stage winner Robert Gesink (LottoNL-Jumbo).
Fast forward to 2015, and Boswell proved himself to be one of the strongest riders on the climb while working in service of Sky teammate Sergio Henao. The American climbing talent was able to ride up to Henao after initially being dropped, and then he paced Henao to the top of the climb to limit his teammate's losses to stage winner Julian Alaphilippe (Quick-Step Floors).
In the end, Henao and Boswell finished together for second and third, respectively, 23 seconds behind the Frenchman. This year Boswell is Team Sky's best-placed GC rider heading into the stage and will have the freedom to race for himself.
"With great responsibility comes great pressure, or something like that," Boswell joked. "But, yeah, I mean it will be nice to give it a go and see what I can do, to go in there with a clear goal of what I need to do for myself."
Making the breakaway and finishing third on stage 2, Boswell put himself in a good position heading into stage 5, which starts in Ontario and climbs Glendora Ridge Road and Glendora Mountain Road before heading for the summit finish on Baldy.
He's currently in third place overall, 14 seconds behind leader Rafal Majka (Bora-Hansgrohe) and 12 seconds behind runner-up George Bennett (LottoNL-Jumbo).
Baldy will provide the final chance for Boswell and the other climbing specialists to create an even bigger buffer between themselves and time trial performers like Andrew Talansky (Cannondale-Drapac) and Brent Bookwalter (BMC Racing). That's especially important to Boswell, who has a dearth of time trial kilometres under his belt this year.
"To be honest, I haven't done a time trial this season," he said. "I did a team time trial in Coppi Bartali, and I did a prologue at Tour de Romandie on a road bike, so we'll see."
Team Sky also has Tao Geoghegan Hart in 12th, 48 seconds back, while next-best-placed David Lopez is 20th, 2:41 down. Although the team still has options to play on the stage, the route often neutralises tactics and the stage comes down to simply who has the best legs.
"I think when you look in years past, that's what it usually come down to," Boswell said. "I don't really see anyone going early. A couple of years ago [Chris] Horner tried to go the first time up Glendora Ridge. I don't think anyone is going to try that. Or maybe now that I've said this they will.
"I would imagine that going into the last 20 minutes, which is what I consider is really the climb, it will be a group of 15-20 guys there and then a selection from there as we saw in 2015."
Shifting gears from domestique role
Terrain and out-of-category climbs aside, one of the biggest challenges Boswell has faced this week is simply shifting his thinking from the domestique role he has played with Team Sky over the past five years to thinking about what it takes to win a race.
"It's been different for myself this week trying to ride GC," Boswell admitted. "I wouldn't say stressful, but you have to be up there and you can't let a time split. If you're not riding GC, a 10 second slip doesn't really matter. So you're definitely burning a bit of extra energy in the peloton.
"It's something completely foreign to me because I've never ridden with any GC aspirations since coming to Sky five years ago," he said.
One of the things Boswell may need to learn is how to get more use out of his teammates. Sometimes selfishness is required to win big races.
"There are little things, like I was trying to move up the side of the peloton, and someone will tell me, like Lawson [Craddock] will say, 'Why is your team not helping you?' But I'm just used to doing this myself. I'm not asking them to help me. We have Viviani here, and I don't want to take resources away from him winning a stage just to protect me on a flat day. I'll be fine."
Being a general classification rider also requires a shift in how one approaches each stage, Boswell said. Riders have to learn how not to lose as much as they need t learn how to win. "All these days were just trying to get through and not lose time, and tomorrow is the only chance that I think Lachlan [Morton] and I have to gain time," he said. "I don't think we're going to put time into Talansky or Bookwalter in the time trial. So it's just trying to not lose time everyday except for one day.
"So it's almost negative racing to a degree. It's not Lachlan's style, especially when he just wants to go out and rip it up exactly like we did on stage 2. That was just fun bike racing, four guys attacking with 50km to go and everyone rolling through. That was just fun bike racing."